Testing system for telephone party-lines.



G. G. BRADBURY.

TESTING SYSTEM FOR TELEPHONE PARTY LINES.

APPLICATION FILED MAR. 25, 1912.

Patented June.16,191

20 l t-h4g4.

WYnEzsses COLUMBIA PLANOGRAPH C0,, WASHINGTON, n. c.

UNITED STATES PATENT OFFICE.

CLIFFORD C. BRADBURY, OF ROCHESTER, NEW YORK, ASSIGNOR TO STROMBEBG-CARLSON TELEPHONE MANUFACTURING COMPANY, OF ROCHESTER, NEW YORK,

A CORPORATION OF NEW YORK.

TESTING SYSTEM FOR TELEPHONE PARTY-LINES.

Specification of Letters Patent.

Patented June 16, 1914.

To all whom it may concern:

Be it known that I, CLIFFORD G. BRAD- BURY, a citizen of the UnitedStates, residing in Rochester, county 01": Monroe, and State of NewYork, have invented certain new and useful Improvements in TestingSystems for Telephone Party-Lines, of which the following is aspecification.

My invention relates to testing systems for telephone party-lines.

The object of my invention is to-provide means for giving the operator apositive indication of the condition of a line which is being tested.

WVhen there are several telephones connected with the same line and onesubscriber on this line desires a connection with another subscriber onthe same line, the operator will test the jack of the desired line, and,with my present invention, will receive a distinctive tone to indicatethat the line tested is the same as the line upon which the calloriginated. The subscriber is then instructed to hang up his receiverwhile the other party on the line is called.

My present invention is an improvement upon the invention of D. A.Lawver and C. C. Bradbury, shown in Patent No. 978,603, December 13,19-10.

- With the system of my present invention,

no tone is produced upon the calling telephone line except when anotherparty on the same line is desired. The calling party, therefore, willsoon become acquainted with the fact that when he hears the busy testtone it is necessary for him to hang up his receiver while the operatorrings the other party on the same line. Furthermore, inasmuch as thetone is only placed upon the sleeve contact of a line upon which arwerting call is desired, the possibility of an operators testing themultiple contact of a jack at the same time that some other operator istesting some other jack in response to a call upon said line, andthereby giving a false tone test to the first operator, is greatlyreduced, since, on an average, the number of reverting calls is onlyabout one in one hundred calls.

In accordance with my present invention, a low resistance relay and asource of current. are placed in a circuit betwe n the sleeve conductorof the answering cord and the test contact of the calling cord so that,when the test contact of the calling cord is c011- nected with thesleeve of a multiple jack which is directly connected with the sleeve ofthe jack to which the answering cord is connected, a low resistancecircuit is completed, causing the actuation of the low resistance relay.The actuation of this low reslstance relay connects a tone-producingdevice with a winding of the operators induction coil and thus gives theoperator a distinct tone, this tone also being inductively received bythe calling subscriber.

My invention is illustrated in the accompanying drawing, wherein allapparatus is shown in its normal or unactuated condition.

Upon the subscribers line here illustrated, four subscribers sets areshown, each provided with a condenser 1 and annunciator 2 in a permanentbridge between line conductors 3 and 4t, and with a transmitter 5 andreceiver 6 in a bridge maintained normally open by contacts of theswitch-hook 7. At the central oflice, line conductor 3 is connectedthrough contacts 8 and 9 of cut-off relay 10, and through the coil ofline relay 11, with the live pole of battery 12. The line conductor 1 isconnected through contacts 13 and 14- of cut-oil relay 10, with earth.Line relay 11 has normally open contacts 15 and 16, adapted, whenclosed, to include the line lamp 17 in circuit with the battery 12. Thecoil of cut-off relay 10 has one terminal connected with earth and theother terminal connected with the sleeve contact 18 of the answeringjack, and with the sleeve or test contacts 19 of the various multiplejacks for said line. Each of the jacks is also provided with tip andring talking circuit cont-acts 20 and 21, the tip con tacts 20 beingconnected with line conductor 41-, and the ring contacts 21 beingconnected with line conductor 3. The cord circuit for connecting withthis line has a tip answering contact 23, connected through conductor24, condenser 25, conductor 26, and the series cont-acts 27 of theoperators ringing key, with the tip or test contact 28 of the callingplug. This cord circuit also has the sleeve answering contact 29,connected through conductor 30, condenser 31, conductor 32,

and the sleeve series contacts 33 of the operators ringing key, to thesleeve contact 34 of the calling plug.

The tip and sleeve supervisory relays 35 and 36 are connected in abridge of the an swering end of the cord circuit, this bridge alsocontaining the battery 12; and the tip and sleeve supervisory relays 37and 38 are connected in a bridge of the calling end of the cord circuit,this bridge also containing the battery 12. Relays 35 and 36 coiiperateto control the answering supervisory signal 39 and relays 37 and'38cotiperate to control the calling supervisory signal 40.

The upper spring 41 of the operators listening key 42 is connected withthe tip contact of the calling plug and through contact 43 connects thecoil of relay 37 with the tip conductor 26. The lower spring 44 of theoperators listening key 42 is connected through conductor 45 with thesleeve conductor 30 of the answering end of the cord circuit. Thenormally disconnected contacts 46 and 47 of the operators listening key42 are adapted, upon the actuation of the key, to connect the condenser48, op- .erators receiver 49 and secondary 50 of the operators inductioncoil in a bridge of the talking strands of the cord circuit. Contact 46is also connected by means of conductor 51 with one terminal of the lowpotential battery 52, this battery being individual to an operatorsposition and not common to the entire exchange. The contact 47 of theoperators listening key 42 is connected through conductor 53, withnormally open contact 54 of the operators test relay 55. The othernormally open contact 56 of test relay is connected through conductor 57and the coil of low resistance reverting test relay 58 with the otherterminal of low potential battery '52. One terminal of the coil of testrelay 55 is connected with earth, while the other terminal is connectedwith the operators bridge at a point between the receiver and thecondenser. The low resistance relay 58 has normally open contacts 59 and60, adapted, when closed, to

I complete the circuit from the tone-producing coil 61, throughconductor 62 and the tertiary winding 63 of the operators inductioncoil, to ground.

In the operation of my system, the removal of the receiver 6 at one ofthe substations upon the telephone line completes the circuit of therelay 11 and displays the line lamp 17. The display of this lampindicates to the operator that a connection is desired upon the linedesignated thereby and she, therefore, inserts her answering plug intothe jack of that line. A circuit is thereby completed from the battery12, through the coil of supervisory relay 36,

,gonduc'tor 30, contacts 29 and 18 of the P and jack, and the coil ofcut-ofi relay 10, to ground, thus actuating relay 10 and interruptingthe circuit of the line relay 11 and etiacing the line lamp 17. Theoperator now actuates her listening key 42 and connects her receiver 49in a bridge between the tip and sleeve strands of the cord circuit. Shethen obtains the desired number and, with her listening key 42 stilldepressed, touches the tip 28 of her calling plug to the sleeve contactof the jack of the desired line. If

y the desired line is busy, by reason of a connection being establishedtherewith through some other cord circuit, the sleeve contact of thejack will be at a potential above that of earth and current will,therefore, flow from the sleeve of the tested jack through the seriescontacts 27 of the operators ringing key, through contacts 41 and 46 ofthe operators listening key 42, the secondary 50 of the operatorsinduction coil, operators receiver 49, and the coil of high resistancetest relay 55, to ground. The current in this path causes a click in theoperators receiver 49 and also actuates high resistance test relay 55.The actuation of this test relay 55 closes its contacts 54 and 56, whichcompletes the circuit from contact 46 of the operators listening key 42,through conductor 51, battery 52, the coil of relay 58, conductor 57,contacts 56 and 54 of relay 55, conductor 53, contacts 47 and 44 of theoperator's listening key 42, conductor 45, to the sleeve conductor 30and sleeve contact 29 of the answering end of the cord circuit. lVhen anordinary line is tested, that is, a line other than the calling line, nocurrent will flow in the path just described, and relay 58 will not beactuated. If, however, the line tested is the one with which theanswering end of the cord circuit is connected, a low resistance circuitis completed from one terminal of the battery 52, through the coil ofrelay 58, conductor 57, contacts 56 and 54 of relay 55, conductor 53,cont acts 47 and 44 of the operators listening key 42, conductor 45,conductor 30, contacts 29 and 18 of the answering plug and ack,conductor 65, sleeve contact 19 of the multiple jack, tip contact 28 ofthe calling plug, series contacts 27 of the ringing key, contacts 41 and46 of operators listening key 42, and conductor 51, to the other pole ofbattery 52. The current in this path will actuate the low resistancerelay 58, closing its contacts 59 and 60, and thus connecting thetone-producing coil 61 in circuit with the tertiary 63 of the operatorsinduction coil. In this manner the operator receives a tone only whentesting the line of the subscriber with which the answering end ofhercord is connected, and the calling subscriber receives the tone onlywhen the operator receives it. After receiving such a test, it iscustomary for the operator to instruct the subscriber to replace thereceiver upon the switch-hook while the bell of the desired subscriberis rung. The operator may then remove either her answering or hercalling cord from the jack of the line which is in use, the current fortalking purposes being thereafter supplied through the supervisoryrelays by means of which one of the supervisory signals 39 or 40 iscontrolled so that the operator is informed when both subscribers on theline replace their receivers at the termination of the conversation.

While my invention is shown and de scribed with respect to a specificform of cord and line circuit, it is to be understood that I do not wishto be unduly limited thereto, it being possible to apply the principlesof my invention to other structures without departing from the spirit orscope thereof.

I claim 1. In a telephone system, the combination with a telephone line,of answering and multiple jacks therefor, multipled testing contacts forsaid jacks, a cord circuit, a common talking battery in permanent bridgeof said cord circuit, an answering sleeve strand and a calling teststrand for said cord circuit, a relay and a source of current eachrendered temporarily individual to said cord circuit and adapted to beconnected in series between said sleeve and said test strands duringtesting, and a special tone circuit closed by the actuation of saidrelay.

2. In a testing system, the combination with jacks having multipletesting contacts, of a cord circuit having a pair of .contacts adaptedto be connected with two of said multiple testing contacts, a source ofcurrent for supplying busy potential to said multiple contacts of thelines when the lines are busy, an electro-magnet and a second source ofcurrent for actuating it connected in a circuit including the two cordcircuit contacts and two multiple jack testing contacts, theenergization of said electro-magnet effecting a signal for the operator.

3. In a testing system, the combination with a cord circuit, a commonbattery in bridge of the talking strands of said cord circuit, of a pairof multipled jack contacts with which the answering and callin ends ofsaid cord circuit may be connecte and a low resistance circuit includinga source of current temporarily rendered individual to the cord circuit,an electro-magnet, a contact of the answering end of the cord, twomultipled jack contacts, and a contact of the calling end of the cord,the current from said source in said path actuating saidelectro-Inagnet, and a signaling circuit completed by the actuation ofsaid electro-magnet.

4. In a telephone system, the combination with a telephone line, of ananswering and a multiple jack for said line at the same operatorsposition, a cord circuit having contacts to register with the contactsof the answering jack for said line, a test contact for said cordcircuit adapted to be connected with the multiple contact for said line,or with the multiple contacts of other lines, a high resistance relayconnected with the test contact of the cord circuit during testing andactuated whenever a busy line is tested, an electro-magnet and a sourceof current connected between the test contact of the answering jack andthe test contact of the calling plug by the actuation of said highresistance relay, said electro-magnet being actuated when the testcontact of the calling plug is connected with the test contact of saidline, but remaining unactuated when the test contact of said plug isconnected with the test contact of another line and a special busysignal controlled by said electro-magnet.

5. In a telephone system, the combination with a telephone line, havinganswering and multipled jacks at the same operators position, of a twoconductor cord circuit having answering and calling ends for connectingwith said jacks, the test contact of the answering jack registering witha talking strand of said cord circuit when the answering plug isinserted into the answering-jack, a test relay, and a tone circuitincluding the calling subscribers line completed by contacts of saidrelay only when the multiple contact of the calling line is tested.

6. In a telephone system, the combination with a telephone line, havingmultipled testing contacts connected with one of the voice currentconductors of the line when a cord is connected with the line at thecentral oflice, of a busy testing circuit at the central oflice, andmeans for said circuit to signal the calling subscriber and the operatoronly when a reverting call is desired.

7. In a telephone cord or connecting circuit, a sleeve contact for theanswering end and a test contact for the calling end of said cordcircuit, an operators listeningkey,acommon source of current and acommon low resist ance relay temporarily associated with the cordcircuit and serially connected between the sleeve contact of theanswering end and the test contact of the calling end of the cordthrough contacts of the operators listoning key when the key isactuated, and a signal circuit completed by the actuation of said relay.

8. In a telephone cord or connecting circuit, an answering sleevecontact, a common source of current and an impedance coil connectedthereto, a low resistance relay, a low voltage source of current, and acalling test contactserially connected together during testing toactuate said relay, current from said common source through saidimpeldance coil being insufficient to actuate said re ay.

9. In a reverting busy test system, a pair of connecting circuitshavingtheir answering ends connected with different lines, a relay for one ofsaid circuits actuated when the calling end of its connecting circuit isconnected with a contact of the same line With which the answering endis connected,

but not actuated when connected With a similar contact of the line withwhich the answering end of the other connecting circuit is connected,and a test circuit completed by said relay.

Signed by me at Rochester, county of Monroe, and State of New York, inthe presence of two Witnesses.

CLIFFORD G. BRADBURY.

Witnesses:

D. P. .CLAUSEN, J. H. LEWIS, Jr.

\Gopies of this patentmay he obtained for five cents each, by addressingthe Commissioner of latcuts,

Washington, D, Q."

